1. Field of Invention
The present invention relates to a manufacturing process for displayers and more particularly to a method for forming contact holes.
2. Related Art
Transistor array substrate is an important and essential component for liquid crystal displays in the consumer market today. In a finished product of conventional transistor array substrate, by applying a plurality of contact holes, a plurality of drains of transistors can be electrically connected to a plurality of pixel electrodes respectively, and signal lines (such as scan lines or data lines) can be electrically connected to drivers.
A conventional transistor array substrate includes two insulation layers, and the contact holes are disposing inside the insulation layers. The contact holes are formed by penetrating at least one of the insulation layers. In other words, some contact holes are formed by penetrating all the insulation layers, or some of them are formed by penetrating one of the insulation layers. Therefore, the contact holes in the same transistor array substrate have different depths.
In general, the contact holes are formed by etching. However, the contact holes have different depths, and thus the drains and signal lines can possibly be damaged due to over-etching during the etching process, such that the transistor array substrate has to be reworked or scrapped. As a result, the manufacturing costs for transistor array substrate are increased.